1) The occurrence of a reinforcement on selected occasions as or after one topography of a performance as opposed to another topography, is called differential reinforcement. For example, one may differentially reinforce performances which exert a great deal of force on the lever as opposed to performances which operate it lightly.

"2) The reinforcement of one class (or form, or topography) of behavior and not another.

3) In producing stimulus control, reinforcement of a behavior under one stimulus condition but not under another stimulus condition. Also, reinforcing one behavior under one stimulus condition as other behaviors are reinforced under different stimulus conditions. "

4) Reinforcement of some responses but not others, depending on the intensive, temporal, topographical, or other properties of the responses (including the stimuli in the presence of which they are emitted; cf. DISCRIMINATED OPERANT); differential reinforcement defines operant classes . When responding has come under the control of differential reinforcement, so that the proportion of responses falling within the limits of the operant class increases, responding is said to be differentiated.

5) Reinforcement which is contingent upon (a) the presence of a given property of a stimulus, in which case the resulting process is discrimination, (b) the presence of a given intensive, durational, or topographical property of a response, in which case the resulting process is differentiation, or (c) a given rate of responding. See also differential rate reinforcement.

6) Involves two or more physically different behaviors; one behavior is reinforced, and all others are extinguished.

7) Any procedure that combines extinction and reinforcement to change the frequency of a target behavior.